Results from sea ice physics explain the observations: For example, an anomaly in ice drift became apparent early this year, pushing thicker ice southward from the west central Arctic. In regions where young ice from the Siberian shelf with their algae carpets was found in 2012 and 2020, heavily melted two-year-old ice dominated this year. As a result, there was hardly any input of material from the ice into the sediment traps and to the seafloor. Oceanographers also noticed an anomaly: The stratification of seawater beneath the ice was locally determined by melting processes or mixing by strong winds, but showed comparatively high salinity. This possibly resulted from overall low melting and reduced input from the freshwater-rich Siberian Shelf Seas. Directly under the ice, at each station planktologists encountered other swarms of animals -such as various jellies, winged snails, amphipods, and copepods. Unlike in 2012, hardly any export of biomass to the deep sea was observed. Even at the end of the melt season, there is still a distinct layer of snow on the sea ice. This makes the ice and ocean below quite dark and leads to the rise of phyto- and zooplankton from deeper water layers to the brighter underside of the ice. In addition, there are hardly any melt ponds on the sea ice, which are otherwise characteristic of the Arctic summer.
Comparisons with sea ice extent during the 2019-2020 MOSAiC Drift Expedition also show that in 2023 more will be left than during the record minima of 2012 and 2020. Despite 2023 being the hottest summer in the world - since weather observations began- sea ice shows an even higher average thicknesses than in previous years. The sea ice physicists and climate modelers explain this phenomenon with a strong low-pressure system influencing the central Arctic weather patterns this year. It remains to be seen how the ice melt will develop until mid-September towards the annual minimum sea ice extent. The first autumn storms are currently transporting warm air towards the Arctic.
Yesterday, the AWI research vessel reached the North Pole on schedule. It is the seventh time in total that in its 42-year history the research icebreaker Polarstern visits the northernmost point of Earth. The ship last reached the North Pole on August 18, 2020, during the MOSAiC expedition lead by Markus Rex. The work, which will last several days, began with a dive to the geographic pole at 90°N in 4224 m water depth. Currently, the scientists are setting up their observatories on the ice floe, in the ocean and on the seafloor. They will then continue their research southwards along 60°E longitude. Polarstern is expected back in Bremerhaven on October 1, 2023.